From 33cdfe9f1943418604be5c800800394ae809fc4c Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Mon, 11 Mar 2013 21:44:37 +0000
Subject: [PATCH] Fix a crasher newly introduced in r176659/r176649, where
 fast-isel tries to lower an expect intrinsic that is a constant expression.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176830 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/FastISel.cpp |  2 ++
 test/CodeGen/X86/fast-isel-expect.ll  | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 test/CodeGen/X86/fast-isel-expect.ll

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index aa45ac59581..10e2dc61499 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -698,6 +698,8 @@ bool FastISel::SelectCall(const User *I) {
   }
   case Intrinsic::expect: {
     unsigned ResultReg = getRegForValue(Call->getArgOperand(0));
+    if (ResultReg == 0)
+      return false;
     UpdateValueMap(Call, ResultReg);
     return true;
   }
diff --git a/test/CodeGen/X86/fast-isel-expect.ll b/test/CodeGen/X86/fast-isel-expect.ll
new file mode 100644
index 00000000000..1f53348bd07
--- /dev/null
+++ b/test/CodeGen/X86/fast-isel-expect.ll
@@ -0,0 +1,23 @@
+; RUN: llc < %s -O0 -march=x86 | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@glbl = extern_weak constant i8
+
+declare i64 @llvm.expect.i64(i64, i64) #0
+
+define void @test() {
+; CHECK: movl $glbl
+  %tmp = call i64 @llvm.expect.i64(i64 zext (i1 icmp eq (i8* @glbl, i8* null) to i64), i64 0)
+  %tmp2 = icmp ne i64 %tmp, 0
+  br i1 %tmp2, label %bb1, label %bb2
+
+bb1:
+  unreachable
+
+bb2:
+  unreachable
+}
+
+attributes #0 = { nounwind readnone }
-- 
2.34.1